1. Field of the Invention
This invention relates to a method and device for above-ground plant growth and root pruning which provides significant advantages over known methods of conducting above-ground plant growth and root pruning.
2. Background Information
In the art of plant and tree horticulture, there have been efforts to develop efficient and cost-effective cultivation systems. Classically, plants, including trees, have been grown in the earth, requiring transplantation to the site of ultimate planting as needed. However, this is a labor and cost-intensive process. Accordingly, certain technologies have been developed in efforts to increase the efficiency of plant growth, including, in certain instances, methods of above-ground plant growth for subsequent transplantation into the earth.
In U.S. Pat. No. 5,768,825 (Reiger, 1998), a set-volume plant preservation bag and method was disclosed. The patent claims require an initial step of field growth of plants which are then transplanted by means of the plant preservation bag and method. The plant preservation bag has an open top, a tapered side and a bottom. The bag can be made of polypropylene, and can be placed around a bag-shaped wire frame if wanted, but is essentially a bag with a bottom, and does not expand like the device of the present invention.
In U.S. Pat. No. 4,888,914 (Reiger, 1989), a method for in-ground growth of plants prior to transplantation is disclosed. The principal purpose of the patented method and device is to control root growth during in-ground growth of the plant, to facilitate subsequent transplantation of the plant. The patent discloses and claims a method and fabric container for controlling root growth. The patent discloses that the fabric container may be made of polypropylene, but includes no discussion of what the container looks like. The picture looks like the container is possibly cylindrical in shape with a bottom. The patent makes no mention of a frame on which the fabric can be placed, and neither discloses nor suggests the idea of a radially expandable container, and is not directed at all to the issues relevant to above-ground growth methodology.
U.S. Pat. No. 5,368,353 (Flanders; Fults, 1994) is directed to a device for carrying and transportation of a burlapped plant to protect the roots of the plant during such transportation. The carrying device is basically a set of straps that connect over the plant ball to ease handling and delivering of the plant. The concept of a radially expandable plant root container is neither disclosed nor suggested.
U.S. Pat. No. 4,646,470 (Maggio, 1987), is directed to a liner for an earth ball surrounding the roots of a plant for transportation. The liner is not intended for purposes of growing the plant above ground. Rather, the patent discloses and claims a fast fit liner for an earth ball formed of a square piece of cloth material with pleats. One can use a rope or drawstring to pull the comers tight around the trunk of the plant or tree. This forms no part of the present invention.
U.S. Pat. No. 4,884,367 (Lawton, 1989), is directed to a root control system for in-ground cultivation of plants by means of a root control bag and a standard probe penetration test for the strength of the bag. The bag can be formed of polypropylene, but does not involve a relatively rigid structure for supporting above-ground plant growth.
U.S. Pat. No. 4,939,865 (Whitcomb; Stephens, 1990), discloses a container for growing transplantable plants comprised of removably joined side panels. The sides are bendable panels joined at the edges by mortise and tenon joints. Therefore, the panels can be bent to form a cylindrically-shaped container. Panels can be added to or removed from the container to increase or decrease the size of the container. Each removable panel is disclosed to be preferably made of thermoplastic material with a lattice of root trapping outwardly pointed recesses on the interior surface. Each of the recesses terminates in a hole for air-root pruning purposes. The container has no bottom and can be placed on a root impervious surface. Although the container can be expanded and is made of a thermoplastic material, there is no mention of a polypropylene fabric cover. In addition, although more panels can be added, the method is more labor intensive than the concentrically expandable device of the present invention.
U.S. Pat. No. 4,807,393 (Bracken, 1989) discloses a root ball container and method, but is not directed to a method of above-ground plant culture and devices for that purpose. Rather, this patent discloses a star-shaped root ball container constructed of a single wire with loops. The star-shaped wire just wraps snugly around the root ball.
U.S. Pat. No. 3,094,810 (Kalpin, 1960), discloses a container for plants which is essentially a semi-rigid vertical structure in which a plant may be grown or shipped. However, no provision is made for the need to expand the volume of the container as additional growth medium is added to accommodate for increased plant trunk diameter, tree and root growth. The only provision for such growth is in the vertical height of the container. The container for plants is made from some semi-rigid material such as plastic, waterproofed paper or cloth, or other suitable material. The container has a bottom with a disc-shaped device to rest in the bottom in order to give the container some support. The patent does not disclose the use of a covering over a rigid mesh structure as in the present invention.
U.S. Pat. No. 5,495,692 (LoJacono, 1996), is directed to a root protection apparatus comprising a collapsible wire basket in combination with a support strap. No provision is made for radial expansion of the volume of the container to accommodate new plant growth medium and increased plant trunk diameter. Rather, this patent discloses a collapsible wire basket that includes a support strap that can be secured across the opening of the basket. The device is for the protection of the plant from underground rodents. The wire basket is for use in a hole previously dug in the ground. The wire mesh protects against the underground rodents.
U.S. Pat. No. 1,894,506 (Wilson, 1931), discloses and claims a plant wrapping means for shipping or storing dormant nursery stock. The package is in the form of a wrapper made of paper, cellophane, burlap, oilcloth or the like and is bound by the use of a cord or wire. The patent makes no mention of the use of polypropylene fabric or the use of a rigid mesh structure, or radial expansion of a container for above-ground growth thereof.
U.S. Pat. No. 4,098,021 (Gruber, 1978) is directed to a plant container specifically directed to growth of dwarfed plants through constriction of the plant root structure. The present invention, by contrast, is directed to a method for enhancing the above-ground growth of plants. The patent discloses and claims a container made of corrosion resistant material, with a plurality of tiny holes in the wall surfaces and open on top. The patent discloses the use of stainless steel, plastics, woven or non-woven material for the container material. The container is filled with nutrient medium and the plant, and is then placed in a bigger pot that is also fitted with nutrient medium.
U.S. Pat. No. 5,454,191 (Mayeda; Mayeda, 1995), is directed to a liner for hanging basket plants. This patent neither discloses, suggests nor claims a radially expandable above-ground plant growth system. Rather, this patent discloses a hanging basket liner for lining wire or other types of hanging baskets, and is therefore far from the device and method of the present invention. The layers of the liner can consist of plastic, synthetic resinous film, non-woven fabric material made of plastic fibers and paper material, joined at a fixed seam.
U.S. Pat. No. 2,140,932 (Avery, 1938), discloses an assemblable pot or plant container, preferably made from leather. The patent neither discloses, suggests, nor claims a radially expandable plant growth container for above-ground plant cultivation. FIG. 5 of the patent discloses a plant container which has interlocking units to form a substantially cylindrical container. However, provision is only made for a single diameter. The disclosed plant container has a fibrous wall structure, containing as its main ingredient treated leather fiber. The container has sidewalls and a bottom.
U.S. Pat. No. 5,393,313 (Reiger, 1995), is directed to a method of in-ground growth of a large number of transplantable seedlings. Radial expansion of a growth container forms no part of this patent disclosure or claims. Rather, a porous fabric which is draped over the ground and previously dug holes is implemented. The fabric conforms to the shape of the holes and growing medium and plants are placed in the fabric-covered holes. Therefore, the patent does not involve the concept of a container or a mesh support structure.
In U.S. Pat. No. 5,937,577 (Butler, 1999), a cylindrically-shaped container for use in nurseries is disclosed. The container consists of wire, such as chicken wire, with a layer of woven polypropylene fabric only on the inside to permit air-root pruning. The cylinder may be placed on the ground or on any suitable material. When a container size over 25 gallons is needed, the chicken wire must be replaced with a heavier gauge wire with squares or rectangular mesh for more support. Due to the fact that the chicken wire must be pre-cut, the container cannot be expanded from its intended size, and the patent makes no mention of coiling or uncoiling the mesh to form a smaller or larger container, dependent on the growth of the plant. In addition, this patent makes no mention of the use of any other material for the support structure, besides different grades of chicken wire.
In U.S. Pat. No. 4,043,077, an expandable plant container to accommodate plant growth was disclosed. The sides of the pot are folded in an accordion-like manner, which expand in response to the growth of the plant. The pot has a bottom, which contains a drain. The pot may be made from plastic or other similar durable material. However, this patent makes no mention of a polypropylene fabric liner. In addition, the structure of the expansion mechanism is completely different from the radially expandable mechanism of the present invention.
In U.S. Pat. No. 5,241,784 (Henry, 1993), a corrugated air root pruning cylindrical container is disclosed having apertures through which plant roots may grow until air contact is made. The patent suggests that xe2x80x9cthe circumference of the container can be varied by using the apertures created for the air root pruning means 30 that are on the same horizontal axis as one of the screw holes 50 . . . The variability of the circumference also enables the nursery owner to allow the roots to expand and grow a larger plant, simply by increasing the circumference of the root pruner and adding growth medium.xe2x80x9d The patent does not disclose a mesh structure over which a porous sheet-like material, such as polypropylene, is supported. The patent makes no mention of use of a needle-punched nonwoven structure such as that preferred according to the present invention.
In U.S. Pat. No. 5,241,783 (Krueger, 1993), discloses an enclosure for plant growth comprising a closed bottom surface, side-walls and an upper enclosing surface having a slit through which a plant may grow. Accordingly, this patent is not directed to the art of air root pruning. The enclosure bears a number of seams by means of which the top, bottom and side surfaces are connected to each other. Materials mentioned for construction of the ""783 device include canvas, which would severely restrict if not completely hinder the possibility of air root pruning. The present invention comprises an embodiment of a bag means which has distinct advantages over the enclosure of the ""783 patent. For example, one embodiment of the present invention comprises an open top, which increases the ease of use and efficiency of production. In addition, the ""783 patent, while mentioning a non-woven porous polymeric material known as DUON in the trade, the patent directly teaches away from non-woven fabrics. By contrast, the present invention identifies non-woven, needle-punched fabrics to be preferred for the air root pruning efficiency.
By contrast to the methods of the cited patents, the present invention provides, in one embodiment, a simple bag-like structure of sufficient rigidity to permit plant growth, root pruning and transplantation thereof. In a further embodiment of this invention, a rigid mesh support structure and a sheet providing multiple microscopic apertures securely draped over both sides of the rigid mesh support structure, i.e. in the sense of a sleeve. The sleeve design of the present invention has distinct advantages for keeping the tree-roots cool and provides advantages in the preparation of the containers and subsequent shipping of the plants (e.g. as by using the outer material layer to wrap the root ball).
This invention relates to a method and device for above-ground plant growth and root pruning which provides significant advantages over known methods of conducting above-ground plant growth and root pruning. The system comprises a non-woven polypropylene or like polymeric fiber fabric of sufficient rigidity in a number of different configurations to permit efficient and stable above-ground plant or tree growth, while maximizing efficiency.